Apparatus and method for an ultrasonic medical device operating in torsional and transverse modes

ABSTRACT

The present invention provides an apparatus and a method for an ultrasonic medical device operating in a torsional mode and a transverse mode. An ultrasonic probe of the ultrasonic medical device is placed in communication with a biological material. An ultrasonic energy source is activated to produce an electrical signal that drives a transducer to produce a torsional vibration of the ultrasonic probe. The torsional vibration produces a component of force in a transverse direction relative to a longitudinal axis of the ultrasonic probe, thereby exciting a transverse vibration along the longitudinal axis causing the ultrasonic probe to undergo both a torsional vibration and a transverse vibration. The torsional vibration and the transverse vibration cause cavitation in a medium surrounding the ultrasonic probe to ablate the biological material.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/774,898, filed on Feb. 9, 2004, the entirety of which is herebyincorporated herein by reference for the teachings therein.

FIELD OF THE INVENTION

The present invention relates to ultrasonic medical devices, and moreparticularly to an apparatus and method of using an ultrasonic probeoperating in torsional and transverse modes.

BACKGROUND OF THE INVENTION

The presence of biological material in various parts of the human bodycan lead to complications ranging from artery disease, heart attack,stroke and in some cases death. The safe and effective destruction ofthe biological material that causes these complications is an importantendeavor in the medical field. A variety of prior art instruments andmethods destroy biological material in the human body.

Prior art medical instruments used to destroy biological material in thebody suffer from several limitations. Prior art medical instruments arelarge, making it difficult for medical professionals to utilize them.Prior art medical instruments utilize high power levels that canadversely affect areas surrounding the treatment area and the patient.Procedures using prior art medical instruments are time consuming incomparison with other methods such as surgical excision.

Prior art medical instruments have relied on longitudinal vibrations ofthe tip of the instrument. By creating longitudinal vibrations of thetip, the tip of the prior art medical instrument must contact thebiological material and, similar to a jackhammer, remove the biologicalmaterial through successive motion of the tip of the instrument. In manycases, the prior art instruments operating in a longitudinal mode have atip having both a small cross sectional area and a small surface area,thereby removing small amounts of biological material and increasing theoverall time of the medical procedure.

For example, U.S. Pat. No. 4,961,424 to Kubota et al. discloses anultrasonic treatment device operating in a longitudinal mode that isurged or brought into contact with an area to be treated, with energydelivered to the tip of the device. U.S. Pat. No. 4,870,953 toDonMicheal et al. discloses an intravascular ultrasonic catheter/probeand method for treating intravascular blockage that delivers ultrasonicenergy via a bulbous tip of the instrument where the bulbous tip isplaced in contact with a blockage. U.S. Pat. No. 5,391,144 to Sakurai etal. discloses an ultrasonic treatment apparatus that includes aninstrument operating in a longitudinal mode that emulsifies tissue atthe tip of the instrument. Therefore, there remains a need in the artfor a device that can safely and effectively destroy a large area ofbiological material in a time efficient manner.

Torsional mode vibration of objects is known in the art. However, theprior art does not describe the torsional mode vibration of a medicaldevice. Further, the prior art requires additional objects to beattached to the prior art instruments, thereby preventing a minimallyinvasive solution of destroying biological material using torsional modevibration. For example, U.S. Pat. No. 4,771,202 and U.S. Pat. No.4,498,025 both to Takahashi disclose a tuning fork using the fundamentalvibration of a flexural mode coupled with the fundamental mode oftorsion. The fundamental frequency of the torsional mode is adjusted byplacing masses near the side edges of the tine tips. U.S. Pat. No.4,652,786 to Mishiro discloses a torsional vibration apparatus having aplurality of electrodes formed on the two surfaces of a circular memberof electrostrictive material. Therefore, there remains a need in the artfor an apparatus and a method of destroying biological material thatutilizes a medical device that can vibrate in a torsional mode todestroy the biological material in the body in a time efficient manner.

The prior art does not provide a solution for destroying biologicalmaterial in a safe, effective and time efficient manner. The prior artdoes not provide an effective solution for increasing a surface area forbiological material destruction. Prior art ultrasonic instruments arelimited in that they require contact between the device and thebiological material and only treat the biological material using the tipof the ultrasonic instrument. Therefore, there remains a need in the artfor an apparatus and a method for an ultrasonic medical device operatingin a torsional mode and a transverse mode to ablate biological materialin a safe, effective and time efficient manner.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and a method for anultrasonic medical device operating in a torsional mode and a transversemode to treat a biological material. The present invention is anultrasonic medical device comprising an ultrasonic probe having aproximal end, a distal end and a longitudinal axis therebetween. Theultrasonic medical device includes a transducer for creating a torsionalvibration of the ultrasonic probe. A coupling engages the proximal endof the ultrasonic probe to a distal end of the transducer. An ultrasonicenergy source engaged to a proximal end of the transducer produces anelectrical energy to power the ultrasonic medical device. The torsionalvibration of the ultrasonic probe induces a transverse vibration alongan active area of the ultrasonic probe, the active area supporting thetorsional vibration and the transverse vibration.

The present invention is a medical device comprising an elongated,flexible probe comprising a proximal end, a distal end and alongitudinal axis between the proximal end and the distal end. Themedical device includes a transducer that converts electrical energyinto mechanical energy, creating a torsional vibration along thelongitudinal axis of the elongated, flexible probe. A coupling engagesthe proximal end of the elongated, flexible probe to a distal end of thetransducer. An ultrasonic energy source engaged to a proximal end of thetransducer provides electrical energy to the transducer. The torsionalvibration induces a transverse vibration along the longitudinal axis ofthe elongated, flexible probe.

The present invention is a method of treating a biological material in abody with an ultrasonic medical device comprising: providing anultrasonic probe having a proximal end, a distal end and a longitudinalaxis therebetween; moving the ultrasonic probe to a treatment site ofthe biological material to place the ultrasonic probe in communicationwith the biological material; activating an ultrasonic energy sourceengaged to the ultrasonic probe to produce an ultrasonic energy that isconverted into a torsional vibration of the ultrasonic probe; andinducing a transverse vibration in an active area of the ultrasonicprobe by the torsional vibration wherein the active area of theultrasonic probe supports the torsional vibration and the transversevibration.

The present invention is a method of removing a biological material in abody comprising providing an ultrasonic medical device comprising aflexible probe having a proximal end, a distal end and a longitudinalaxis between the proximal end and the distal end. The flexible probe ismoved in the body and placed in communication with the biologicalmaterial. An ultrasonic energy source of the ultrasonic medical deviceis activated to produce an electrical signal that drives a transducer ofthe ultrasonic medical device to produce a torsional vibration of theflexible probe. The torsional vibration induces a transverse vibrationalong the longitudinal axis of the ultrasonic probe.

The present invention provides an apparatus and a method for anultrasonic medical device operating in a torsional mode and a transversemode. The active area of the ultrasonic probe operating in the torsionalmode and the transverse mode is vibrated in a direction not parallel tothe longitudinal axis of the ultrasonic probe while equally spacedpoints along the active area are vibrated back and forth in a short arcin a plane parallel to the longitudinal axis along the active area ofthe ultrasonic probe. The present invention provides an ultrasonicmedical device that is simple, user-friendly, time efficient, reliableand cost effective.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained with reference to theattached drawings, wherein like structures are referred to by likenumerals throughout the several views. The drawings shown are notnecessarily to scale, with emphasis instead generally being placed uponillustrating the principles of the present invention.

FIG. 1 is a side plan view of an ultrasonic medical device of thepresent invention capable of operating in a torsional mode and atransverse mode.

FIG. 2 is a side plan view of an ultrasonic probe of the presentinvention having a uniform diameter from a proximal end of theultrasonic probe to a distal end of the ultrasonic probe.

FIG. 3 is a fragmentary perspective view of an ultrasonic probe of thepresent invention having a torsional vibration and a transversevibration along an active area of the ultrasonic probe.

FIG. 4 is a fragmentary perspective view of the ultrasonic probe of thepresent invention undergoing a torsional vibration.

FIG. 5A is a fragmentary side plan view of the ultrasonic probe of thepresent invention undergoing a torsional vibration.

FIG. 5B is a graph corresponding to the torsional vibration shown inFIG. 5A.

FIG. 6 is a fragmentary side plan view of the ultrasonic probe of thepresent invention undergoing a transverse vibration.

FIG. 7 is a fragmentary perspective view of the ultrasonic probe of thepresent invention undergoing a transverse vibration along an active areaof the ultrasonic probe and a torsional vibration along a sectionproximal to the active area of the ultrasonic probe.

FIG. 8 is a fragmentary side plan view of the ultrasonic probe of thepresent invention having a plurality of nodes and a plurality ofanti-nodes along an active area of the ultrasonic probe.

FIG. 9 is a fragmentary perspective view of a portion of a longitudinalaxis of an ultrasonic probe of the present invention comprising anapproximately circular cross section at a proximal end of the ultrasonicprobe and a radially asymmetric cross section at a distal end of theultrasonic probe.

FIG. 10 is a side plan view of the ultrasonic probe of the presentinvention located within a sheath.

While the above-identified drawings set forth preferred embodiments ofthe present invention, other embodiments of the present invention arealso contemplated, as noted in the discussion. This disclosure presentsillustrative embodiments of the present invention by way ofrepresentation and not limitation. Numerous other modifications andembodiments can be devised by those skilled in the art which fall withinthe scope and spirit of the principles of the present invention.

DETAILED DESCRIPTION

The present invention provides an apparatus and a method for using anultrasonic medical device vibrating in a torsional mode and transversemode to treat a biological material. The ultrasonic medical devicecomprises an ultrasonic probe, a transducer, a coupling engaging aproximal end of the ultrasonic probe to a distal end of the transducerand an ultrasonic energy source engaged to a proximal end of thetransducer. The ultrasonic energy source produces an ultrasonic energythat is transmitted to the transducer, where the transducer creates atorsional vibration of the ultrasonic probe. The torsional vibrationinduces a transverse vibration along an active area of the ultrasonicprobe, creating a plurality of nodes and a plurality of anti-nodes alongthe active area resulting in cavitation along the active area. Theactive area of the ultrasonic probe supports the torsional vibration andthe transverse vibration.

The following terms and definitions are used herein:

“Ablate” as used herein refers to removing, clearing, destroying ortaking away a biological material. “Ablation” as used herein refers to aremoval, clearance, destruction, or taking away of the biologicalmaterial.

“Node” as used herein refers to a region of a minimum energy emitted byan ultrasonic probe at or proximal to a specific location along alongitudinal axis of the ultrasonic probe.

“Anti-node” as used herein refers to a region of a maximum energyemitted by an ultrasonic probe at or proximal to a specific locationalong a longitudinal axis of the ultrasonic probe.

“Probe” as used herein refers to a device capable of propagating anenergy emitted by the ultrasonic energy source along a longitudinal axisof the ultrasonic probe, resolving the energy into an effectivecavitational energy at a specific resonance (defined by a plurality ofnodes and a plurality of anti-nodes along an “active area” of the probe)and is capable of an acoustic impedance transformation of an ultrasoundenergy to a mechanical energy.

“Biological material” as used herein refers to a collection of a matterincluding, but not limited to, a group of similar cells, intravascularblood clots or thrombus, fibrin, calcified plaque, calcium deposits,occlusional deposits, atherosclerotic plaque, fatty deposits, adiposetissues, atherosclerotic cholesterol buildup, fibrous material buildup,arterial stenoses, minerals, high water content tissues, platelets,cellular debris, wastes and other occlusive materials.

“Vibration” as used herein refers to movement wherein portions of anobject move alternately in opposite directions from a position ofequilibrium. Vibration also refers to motion, oscillation and wavepropagation.

An ultrasonic medical device capable of operating in a torsional modeand transverse mode is illustrated generally at 11 in FIG. 1. Theultrasonic medical device 11 includes an ultrasonic probe 15 which iscoupled to an ultrasonic energy source or generator 99 for theproduction of an ultrasonic energy. A handle 88, comprising a proximalend 87 and a distal end 86, surrounds a transducer within the handle 88.The transducer, having a proximal end engaging the ultrasonic energysource 99 and a distal end coupled to a proximal end 31 of theultrasonic probe 15, transmits the ultrasonic energy to the ultrasonicprobe 15. A connector 93 and a connecting wire 98 engage the ultrasonicenergy source 99 to the transducer. The ultrasonic probe 15 includes theproximal end 31, a distal end 24 that ends in a probe tip 9 and alongitudinal axis between the proximal end 31 and the distal end 24. Ina preferred embodiment of the present invention shown in FIG. 1, adiameter of the ultrasonic probe decreases from a first defined interval26 to a second defined interval 28 along the longitudinal axis of theultrasonic probe 15 over a diameter transition 82. A coupling 33 thatengages the proximal end 31 of the ultrasonic probe 15 to the transducerwithin the handle 88 is illustrated generally in FIG. 1. In a preferredembodiment of the present invention, the coupling is a quickattachment-detachment system. An ultrasonic medical device with a quickattachment-detachment system is described in the Assignee's co-pendingpatent applications U.S. Ser. No. 09/975,725; U.S. Ser. No. 10/268,487and U.S. Ser. No. 10/268,843, and the entirety of all these applicationsare hereby incorporated herein by reference.

FIG. 2 shows an alternative embodiment of the ultrasonic probe 15 of thepresent invention. In the embodiment of the present invention shown inFIG. 2, the diameter of the ultrasonic probe 15 is approximately uniformfrom the proximal end 31 of the ultrasonic probe 15 to the distal end 24of the ultrasonic probe 15.

In a preferred embodiment of the present invention, the ultrasonic probe15 is a wire.

In a preferred embodiment of the present invention, a cross section ofthe ultrasonic probe is approximately circular from the proximal end 31of the ultrasonic probe 15 to the distal end 24 of the ultrasonic probe15. In an embodiment of the present invention, the ultrasonic probe 15is elongated. In an embodiment of the present invention, the diameter ofthe ultrasonic probe 15 decreases at greater than two defined intervals.In an embodiment of the present invention, the diameter transitions 82of the ultrasonic probe 15 are tapered to gradually change the diameterfrom the proximal end 31 to the distal end 24 along the longitudinalaxis of the ultrasonic probe 15. In another embodiment of the presentinvention, the diameter transitions 82 of the ultrasonic probe 15 arestepwise to change the diameter from the proximal end 31 to the distalend 24 along the longitudinal axis of the ultrasonic probe 15. Thoseskilled in the art will recognize that there can be any number ofdefined intervals and diameter transitions, and that the diametertransitions can be of any shape known in the art and be within thespirit and scope of the present invention.

In an embodiment of the present invention, the gradual change of thediameter from the proximal end 31 to the distal end 24 occurs over theat least one diameter transitions 82, with each diameter transition 82having an approximately equal length. In another embodiment of thepresent invention, the gradual change of the diameter from the proximalend 31 to the distal end 24 occurs over a plurality of diametertransitions 82 with each diameter transition 82 having a varying length.The diameter transition 82 refers to a section where the diameter variesfrom a first diameter to a second diameter.

The probe tip 9 can be any shape including, but not limited to, bent, aball or larger shapes. In one embodiment of the present invention, theultrasonic energy source 99 is a physical part of the ultrasonic medicaldevice 11. In another embodiment of the present invention, theultrasonic energy source 99 is not an integral part of the ultrasonicmedical device 11. The ultrasonic probe 15 is used to treat a biologicalmaterial and may be disposed of after use. In a preferred embodiment ofthe present invention, the ultrasonic probe 15 is for a single use andon a single patient. In a preferred embodiment of the present invention,the ultrasonic probe 15 is disposable. In another embodiment of thepresent invention, the ultrasonic probe 15 can be used multiple times.

The ultrasonic probe 15 has a stiffness that gives the ultrasonic probe15 a flexibility allowing the ultrasonic probe 15 to be deflected andarticulated when the ultrasonic medical device 11 is in motion. Theultrasonic probe 15 can be bent, flexed and deflected to reach thebiological material at locations in the vasculature of the body that aredifficult to reach. The ultrasonic probe 15 has a flexibility to supporta torsional vibration and a transverse vibration.

In a preferred embodiment of the present invention, the ultrasonic probe15 comprises a substantially uniform cross section from the proximal end31 to the distal end 24. In a preferred embodiment of the presentinvention, a cross section of the ultrasonic probe 15 is approximatelycircular. In another embodiment of the present invention, a portion ofthe longitudinal axis of the ultrasonic probe 15 is radially asymmetric.In another embodiment of the present invention, the cross section of theultrasonic probe 15 is spline shaped with a plurality of projectionsextending from an outer surface of the ultrasonic probe 15. In anotherembodiment of the present invention, the shape of the cross section ofthe ultrasonic probe 15 includes, but is not limited to, square,trapezoidal, elliptical, rectangular, oval, triangular, circular with aflat spot and similar cross sections. Those skilled in the art willrecognize that other cross sectional geometries known in the art wouldbe within the spirit and scope of the present invention.

In another embodiment of the present invention, the ultrasonic probecomprises a varying cross section from the proximal end 31 of theultrasonic probe 15 to the distal end 24 of the ultrasonic probe 15.Various cross sectional shapes including, but not limited to square,trapezoidal, elliptical, spline shaped, rectangular, oval, triangular,circular with a flat spot and similar cross sections can be used tomodify the active area.

In a preferred embodiment of the present invention, the ultrasonic probe15 comprises titanium or a titanium alloy. In a preferred embodiment ofthe present invention, the ultrasonic probe 15 comprises titanium alloyTi-6A1-4V. The elements comprising Ti-6A1-4V and the representativeelemental weight percentages of Ti-6A1-4V are titanium (about 90%),aluminum (about 6%), vanadium (about 4%), iron (maximum about 0.25%) andoxygen (maximum about 0.2%). Titanium is a strong, flexible, lowdensity, low radiopacity and easily fabricated metal that is used as astructural material. Titanium and its alloys have excellent corrosionresistance in many environments and have good elevated temperatureproperties. In another embodiment of the present invention, theultrasonic probe 15 comprises stainless steel. In another embodiment ofthe present invention, the ultrasonic probe 15 comprises an alloy ofstainless steel. In another embodiment of the present invention, theultrasonic probe 15 comprises aluminum. In another embodiment of thepresent invention, the ultrasonic probe 15 comprises an alloy ofaluminum. In another embodiment of the present invention, the ultrasonicprobe 15 comprises a combination of titanium and stainless steel. Thoseskilled in the art will recognize that the ultrasonic probe can becomprised of many other materials known in the art and be within thespirit and scope of the present invention.

In a preferred embodiment of the present invention, the ultrasonic probe15 has a small diameter. In an embodiment of the present invention, thediameter of the ultrasonic probe 15 gradually decreases from theproximal end 31 to the distal end 24. In an embodiment of the presentinvention, the diameter of the distal end 24 of the ultrasonic probe 15is about 0.004 inches. In another embodiment of the present invention,the diameter of the distal end 24 of the ultrasonic probe 15 is about0.015 inches. In other embodiments of the present invention, thediameter of the distal end 24 of the ultrasonic probe 15 varies betweenabout 0.003 inches and about 0.025 inches. Those skilled in the art willrecognize an ultrasonic probe 15 can have a diameter at the distal end24 smaller than about 0.003 inches, larger than about 0.025 inches, andbetween about 0.003 inches and about 0.025 inches and be within thespirit and scope of the present invention.

In an embodiment of the present invention, the diameter of the proximalend 31 of the ultrasonic probe 15 is about 0.012 inches. In anotherembodiment of the present invention, the diameter of the proximal end 31of the ultrasonic probe 15 is about 0.025 inches. In other embodimentsof the present invention, the diameter of the proximal end 31 of theultrasonic probe 15 varies between about 0.003 inches and about 0.025inches. Those skilled in the art will recognize the ultrasonic probe 15can have a diameter at the proximal end 31 smaller than about 0.003inches, larger than about 0.025 inches, and between about 0.003 inchesand about 0.025 inches and be within the spirit and scope of the presentinvention.

The length of the ultrasonic probe 15 of the present invention is chosenso as to be resonant in a torsional mode and a transverse mode. In anembodiment of the present invention, the ultrasonic probe 15 is betweenabout 30 centimeters and about 300 centimeters in length. For theultrasonic probe 15 to operate in the torsional mode and the transversemode, the ultrasonic probe 15 should be detuned from the transducer,meaning that the length of the ultrasonic probe 15 should not be aninteger multiple of one-half wavelength of the fundamental torsionalresonance of the transducer. The ultrasonic probe 15 is detuned from thetransducer when the resonant frequency of the ultrasonic probe 15 isdifferent from the resonant frequency of the transducer. The sectionbelow entitled “Theory of Operation” provides details and equations fordetermining the length for the ultrasonic probe operating in thetorsional mode and the transverse mode. For example, for an ultrasonicprobe comprised of titanium operating at a frequency of 20 kHz, thelength of the ultrasonic probe should not be an integer multiple ofone-half wavelength (approximately 7.58 centimeters (about 3 inches)).Those skilled in the art will recognize an ultrasonic probe can have alength shorter than about 30 centimeters, a length longer than about 300centimeters and a length between about 30 centimeters and about 300centimeters and be within the spirit and scope of the present invention.

The handle 88 surrounds the transducer located between the proximal end31 of the ultrasonic probe 15 and the connector 93. In a preferredembodiment of the present invention, the transducer includes, but is notlimited to, a horn, an electrode, an insulator, a backnut, a washer, apiezo microphone, and a piezo drive. The transducer converts electricalenergy provided by the ultrasonic energy source 99 to mechanical energyand sets the operating frequency of the ultrasonic medical device 11. Byan appropriately oriented and driven cylindrical array of piezoelectriccrystals of the transducer, the horn creates a torsional wave along atleast a portion of the longitudinal axis of the ultrasonic probe 15,causing the ultrasonic probe 15 to vibrate in a torsional mode with atorsional vibration. The transducer crystals are vibrated in a directionapproximately tangential to the cylindrical surface of the ultrasonicprobe 15. U.S. Pat. No. 2,838,695 to Thurston describes how anappropriately oriented and driven cylindrical array of transducercrystals creates torsional waves, and the entirety of this patent ishereby incorporated herein by reference. The transducer transmitsultrasonic energy received from the ultrasonic energy source 99 to theultrasonic probe 15, causing the ultrasonic probe 15 to vibrate in atorsional mode. The transducer is capable of engaging the ultrasonicprobe 15 at the proximal end 31 with sufficient restraint to form anacoustical mass that can propagate the ultrasonic energy provided by theultrasonic energy source 99.

The ultrasonic probe 15 is moved to a treatment site of the biologicalmaterial and the ultrasonic probe 15 is placed in communication with thebiological material. The ultrasonic probe 15 may be swept, twisted orrotated along the treatment site of the biological material. Thoseskilled in the art will recognize the ultrasonic probe can be placed incommunication with the biological material in many other ways known inthe art and be within the spirit and scope of the present invention.

The ultrasonic energy source 99 is activated to produce the ultrasonicenergy that produces a torsional vibration of the ultrasonic probe 15.The ultrasonic energy source 99 provides the electrical power to thetransducer at the resonant frequency of the transducer. The ultrasonicenergy source 99 provides a low power electric signal of between about 2watts to about 15 watts to the transducer that is located within thehandle 88. Piezoelectric ceramic crystals inside the transducer create atorsional vibration that is converted into a standing torsional wavealong the longitudinal axis of the ultrasonic probe 15. In a preferredembodiment of the present invention, the ultrasonic energy source 99finds the resonant frequency of the transducer through a Phase Lock Loop(PLL) circuit.

The torsional wave is transmitted along the longitudinal axis of theultrasonic probe 15. The torsional wave produces a component of force ina transverse direction relative to the longitudinal axis of theultrasonic probe 15, thereby exciting a transverse wave along thelongitudinal axis of the ultrasonic probe 15. As a result, theultrasonic probe 15 undergoes both a torsional vibration and atransverse vibration.

The torsional vibration along the longitudinal axis of the ultrasonicprobe 15 induces a transverse vibration along an active area of theultrasonic probe 15. In a preferred embodiment of the present invention,the active area is at least a portion of the longitudinal axis of theultrasonic probe 15. In an embodiment of the present invention, theactive area is at the distal end 24 of the ultrasonic probe 15. Thoseskilled in the art will recognize the active area can be locatedanywhere along the longitudinal axis of the ultrasonic probe and theactive area can have varying lengths and be within the spirit and scopeof the present invention.

FIG. 3 shows a perspective view of the ultrasonic probe 15 of thepresent invention undergoing a torsional vibration and a transversevibration along the active area of the ultrasonic probe 15. Thetorsional vibration is shown as the alternating clockwise andcounterclockwise sets of arrows, with each set comprising five arrows inFIG. 3. The transverse vibration is shown with a wave-like motion in arepeating form where the vibration rises from the longitudinal axis to amaximum amplitude, descends back down to the longitudinal axis to aminimum amplitude, proceeds from the longitudinal axis to a maximumamplitude and returns to the longitudinal axis of the ultrasonic probe15.

Depending upon physical properties (i.e. length, diameter, etc.) andmaterial properties (i.e., yield strength, modulus, etc.) of theultrasonic probe 15, the transverse vibration is excited by thetorsional vibration. The active area of the ultrasonic probe 15undergoes both the torsional vibration and the transverse vibration. Byvibrating the ultrasonic probe 15 both torsionally and transversely, theultrasonic probe 15 is operated in a torsional mode of vibration and atransverse mode of vibration. Coupling of the torsional mode ofvibration and the transverse mode of vibration is possible because ofcommon shear components for the elastic forces. The transverse vibrationis induced when the frequency of the transducer is close to a transverseresonant frequency of the ultrasonic probe 15. The combination of thetorsional mode of vibration and the transverse mode of vibration ispossible because for each torsional mode of vibration, there are manyclose transverse modes of vibration.

The torsional wave motion along the longitudinal axis of the ultrasonicprobe 15 creates a shear force gradient along the longitudinal axis ofthe ultrasonic probe 15. The shear force gradient generates a transversemotion when the frequency of the torsional motion is close to atransverse resonant frequency of the ultrasonic probe 15. The shearforce is in the approximate same direction as the transverse motion. Themagnitude of the shear force is proportional to the torsional or angulardisplacement. As shown in FIG. 3, the wavelength for the transverse modeof vibration is less than the wavelength for the torsional mode ofvibration. In an embodiment of the present invention, two or morewavelengths for the transverse mode of vibration are produced for onewavelength for the torsional mode of vibration. In the embodiment of thepresent invention shown in FIG. 3, the transverse vibration wavelengthis about one-fifth (⅕) of the torsional vibration wavelength.

By applying tension to the ultrasonic probe 15, the transverse andtorsional vibrations are shifted in frequency. For example, bending theultrasonic probe 15 causes the transverse and torsional vibration toshift in frequency. Bending the ultrasonic probe 15 causes a shift infrequency resulting from the changes in tension. In an embodiment of thepresent invention, the ultrasonic probe 15 is coupled to the transducerthrough an acoustic impedance mismatch so that the tuning of theultrasonic probe 15 will not affect the drive frequency. The acousticimpedance mismatch can be achieved by maintaining a large differencebetween the moment of inertia of the transducer and the moment ofinertia of the ultrasonic probe 15. The acoustic impedance mismatch canbe created by a discontinuity at the transducer or created further downthe longitudinal axis of the ultrasonic probe 15 by reducing thediameter in a stepwise manner toward the distal end 24 of the ultrasonicprobe 15. An ultrasonic probe device having an impedance mismatch withrapid attachment and detachment means is described in Assignee'sco-pending patent application U.S. Ser. No. 10/268,487, the entirety ofwhich is hereby incorporated herein by reference.

FIG. 4 shows a fragmentary perspective view of the ultrasonic probe 15of the present invention undergoing the torsional vibration. Asdiscussed above, the alternating clockwise and counterclockwise arrowsrepresent the torsional vibration, showing the rotational andcounterrotational motion of the ultrasonic probe 15. FIG. 5A shows afragmentary side plan view of the ultrasonic probe 15 of the presentinvention undergoing the torsional vibration while FIG. 5B shows a graphcorresponding to the torsional vibration shown in FIG. 5A.

FIG. 6 shows the ultrasonic probe 15 undergoing the transversevibration. To clearly describe the torsional vibration and thetransverse vibration, the torsional vibration will be examined whilediscussing FIG. 4, FIG. 5A and FIG. 5B while the transverse vibrationwill be separately examined while discussing FIG. 6.

The torsional vibration of the ultrasonic probe 15 in FIG. 4 and FIG. 5Ais shown as movement of the ultrasonic probe in alternating clockwiseand counterclockwise directions along the longitudinal axis of theultrasonic probe 15. The torsional vibration shown in FIG. 4 and FIG. 5Ais a torsional oscillation whereby equally spaced points along thelongitudinal axis of the ultrasonic probe 15 including the probe tip 9vibrate back and forth in a short arc of the same amplitude in a planeperpendicular to the longitudinal axis of the ultrasonic probe 15. Thevibration creates a plurality of torsional nodes 50 and a plurality oftorsional antinodes 52 along an active area of the ultrasonic probe 15.A section proximal to each of the plurality of torsional nodes 50 and asection distal to each of the plurality of torsional nodes 50 arevibrated out of phase, with the proximal section vibrated in a clockwisedirection and the distal section vibrated in a counterclockwisedirection, or vice versa. The torsional vibration produces a rotationand counterrotation along the longitudinal axis of the ultrasonic probe15. As shown in FIG. 5A and FIG. 5B, the torsional vibration ispropagated in a forward direction and a reverse direction about atorsional node 50. Traveling along the longitudinal axis, at eachtorsional node 50, the direction of the rotation reverses and theamplitude increases until reaching a torsional anti-node 52 andsubsequently decreases toward the next torsional node 50. An ultrasonicprobe operating in a torsional mode for biological material ablation aredescribed in the Assignee's co-pending patent application U.S. Ser. No.10/774,985 filed Feb. 9, 2004, and the entirety of this application ishereby incorporated herein by reference.

FIG. 5A shows the alternating clockwise and counterclockwise motionabout the torsional node 50 and shows an expansion and a compression ofthe ultrasonic probe 15 in the torsional mode. FIG. 5A shows theexpansion of the ultrasonic probe 15 as the clockwise andcounterclockwise motion of the ultrasonic probe 15 extends away from thetorsional node 50. As the alternating clockwise and counterclockwisemotion returns back to the torsional node 50, the ultrasonic probe 15 iscompressed. The ultrasonic probe 15 will expand and compress about theplurality of torsional nodes 50 along an active area of the ultrasonicprobe 15.

The transverse vibration of the ultrasonic probe 15 shown in FIG. 6results in a portion of the longitudinal axis of the ultrasonic probe 15vibrated in a direction not parallel to the longitudinal axis of theultrasonic probe 15. The transverse vibration results in movement of thelongitudinal axis of the ultrasonic probe 15 in a directionapproximately perpendicular to the longitudinal axis of the ultrasonicprobe 15. The transverse vibration creates a plurality of transversenodes 60 and a plurality of transverse anti-nodes 62 along the activearea of the ultrasonic probe 15. Transversely vibrating ultrasonicprobes for biological material ablation are described in the Assignee'sU.S. Pat. Nos. 6,551,337 and 6,652,547 and co-pending patent applicationU.S. Ser. No. 09/917,471, which further describe the design parametersfor such an ultrasonic probe and its use in ultrasonic devices for anablation, and the entirety of these patents and patent applications arehereby incorporated herein by reference.

As best shown in FIG. 3, the torsional vibration shown in FIG. 4 and thetransverse vibration shown in FIG. 6 are combined at the active area ofthe ultrasonic probe 15 to produce the torsional vibration andtransverse vibration shown in FIG. 3. The torsional vibration and thetransverse vibration create a plurality of nodes 50, 60 and a pluralityof antinodes 52, 62 along the active area of the ultrasonic probe 15. Inthe torsional mode of vibration and the transverse mode of vibration,the active area of the ultrasonic probe 15 is vibrated in a directionnot parallel to the longitudinal axis of the ultrasonic probe 15 whileequally spaced points along the longitudinal axis of the ultrasonicprobe 15 in a proximal section vibrate back and forth in a short arcabout the longitudinal axis of the ultrasonic probe 15. In a preferredembodiment of the present invention, the torsional vibration and thetransverse vibration are superimposed over the active area of theultrasonic probe 15 (FIG. 3).

In an alternative embodiment of the present invention shown in FIG. 7,the torsional vibration of the ultrasonic probe 15 creates thetransverse vibration along an active area of the ultrasonic probe, wherethe active area undergoes the transverse vibration without the torsionalvibration. The transverse vibration creates the plurality of transversenodes 60 and the plurality of transverse anti-nodes 62 along thelongitudinal axis of the ultrasonic probe 15. FIG. 7 shows thealternative embodiment wherein the torsional vibration and thetransverse vibration are segregated over the longitudinal axis of theultrasonic probe 15. In one embodiment, a segregation section of theultrasonic probe 15 is between the torsional vibration and thetransverse vibration. In another embodiment, there is a minor overlap ofthe torsional vibration and the transverse vibration over the activearea of the ultrasonic probe 15. Those skilled in the art will recognizea length of the segregation section between the torsional vibration andthe transverse vibration can vary and be within the spirit and scope ofthe present invention.

FIG. 8 shows a fragmentary perspective view of the ultrasonic probe 15with the plurality of nodes 50, 60 and the plurality of anti-nodes 52,62 for the torsional mode of vibration and the transverse mode ofvibration along the active area of the ultrasonic probe 15 caused by thetorsional vibration and the transverse vibration of the ultrasonic probe15. FIG. 8 and FIG. 3 both show the pattern of the plurality of nodes50, 60, and the plurality of antinodes 52, 62 for the torsional mode ofvibration and the transverse mode of vibration are independently createdfor each mode of vibration. As a result, the pattern of the plurality ofnodes 50, 60 and the plurality of anti-nodes 52, 62 has a differentspacing for the torsional mode of vibration and the transverse mode ofvibration. The plurality of nodes 50, 60 are areas of minimum energy andminimum vibration. The plurality of anti-nodes 52, 62, areas of maximumenergy and maximum vibration, also occur at repeating intervals alongthe active area of the ultrasonic probe 15. The torsional vibration andthe transverse vibration at the active area of the ultrasonic probe 15create the plurality of nodes 50, 60 and the plurality of anti-nodes 52,62 along the active area of the ultrasonic probe 15 resulting incavitation in a medium surrounding the ultrasonic probe 15 that ablatesthe biological material.

The combined torsional motion and transverse motion of the ultrasonicprobe 15 caused by the torsional vibration and the transverse vibrationcauses an interaction between the surface of the ultrasonic probe 15 andthe medium surrounding the ultrasonic probe 15 to cause an acoustic wavein the medium surrounding the ultrasonic probe 15. In effect, acousticenergy is generated in the medium surrounding the ultrasonic probe 15.The motion caused by the torsional vibration and the transversevibration causes cavitation in the medium surrounding the ultrasonicprobe 15 over an active area of the ultrasonic probe 15.

Cavitation is a process in which small voids are formed in a surroundingfluid through the rapid motion of the ultrasonic probe 15 and the voidsare subsequently forced to compress. The compression of the voidscreates a wave of acoustic energy which acts to dissolve the matrixbinding the biological material, while having no damaging effects onhealthy tissue. The biological material is resolved into a particulatehaving a size on the order of red blood cells (approximately 5 micronsin diameter). The size of the particulate is such that the particulateis easily discharged from the body through conventional methods orsimply dissolves into the blood stream. A conventional method ofdischarging the particulate from the body includes transferring theparticulate through the blood stream to the kidney where the particulateis excreted as bodily waste.

The torsional motion of the ultrasonic probe 15 is less than thetransverse motion of the ultrasonic probe 15. Once the transverse motionis established on the ultrasonic probe 15, almost all additional energygoes into transverse motion and the amplitude of the torsional motiondoes not increase appreciably past this point. Cavitation is createdprimarily because of the transverse motion of the ultrasonic probe 15.

The number of nodes 50, 60 and the number of anti-nodes 52, 62 occurringalong the active area of the ultrasonic probe 15 is modulated bychanging the frequency of energy supplied by the ultrasonic energysource 99. The exact frequency, however, is not critical and theultrasonic energy source 99 run at, for example, about 20 kHz issufficient to create an effective number of biological materialdestroying anti-nodes 52, 62 along the longitudinal axis of theultrasonic probe 15. The low frequency requirement of the presentinvention is a further advantage in that the low frequency requirementleads to less damage to healthy tissue. Those skilled in the art willrecognize that changing the dimensions of the ultrasonic probe 15,including diameter, length and distance to the ultrasonic energy source99, will affect the number and spacing of the nodes 50, 60 and theanti-nodes 52, 62 along the active area of the ultrasonic probe 15.

The present invention allows the use of ultrasonic energy to be appliedto the biological material selectively, because the ultrasonic probe 15conducts energy across a frequency range from about 10 kHz through about100 kHz. The amount of ultrasonic energy to be applied to a particulartreatment site is a function of the amplitude and frequency of vibrationof the ultrasonic probe 15. In general, the amplitude or throw rate ofenergy is in the range of about 25 microns to about 250 microns, and thefrequency in the range of about 10 kHz to about 100 kHz. In a preferredembodiment of the present invention, the frequency of ultrasonic energyis from about 20 kHz to about 35 kHz.

As discussed above, once the transverse motion of the ultrasonic probe15 is established, almost all additional energy goes into transversemotion of the ultrasonic probe 15 and the amplitude of the torsionalmotion does not increase appreciably past this point. As such, in thepreferred embodiment of the present invention, the torsional motion ofthe ultrasonic probe 15 is less than the transverse motion of theultrasonic probe 15.

FIG. 9 shows a perspective view of another embodiment of the presentinvention where the cross section of the ultrasonic probe 15 varies fromthe proximal end 31 of the ultrasonic probe 15 to the distal end 24 ofthe ultrasonic probe 15. In the embodiment of the present inventionshown in FIG. 9, the cross section of the ultrasonic probe varies froman approximately circular cross at the proximal end 31 of the ultrasonicprobe 15 to a radially asymmetric cross section at the distal end 24 ofthe ultrasonic probe 15. In FIG. 9, the radially asymmetric crosssection at the distal end 24 of the ultrasonic probe 15 is approximatelyrectangular. Other radially asymmetric cross sections at the distal end24 of the ultrasonic probe 15 that can be used to create torsionalmotion that subsequently produces cavitation along a portion of thelength of the longitudinal axis include, but are not limited to, square,trapezoidal, elliptical, star shaped, rectangular, oval, triangular,circular with a flat spot and similar cross sections. Those skilled inthe art will recognize other radially asymmetric cross sections known inthe art are within the spirit and scope of the present invention.

The torsional vibration and the transverse vibration of the ultrasonicprobe 15 according to the present invention differ from an axial (orlongitudinal) mode of vibration disclosed in the prior art. Rather thanvibrating in an axial direction, the ultrasonic probe 15 of the presentinvention vibrates both torsionally and transversely along the activearea of the ultrasonic probe 15. As a consequence of the torsionalvibration and the transverse vibration of the ultrasonic probe 15, thebiological material destroying effects of the ultrasonic medical device11 are not limited to the tip of the ultrasonic probe 15. Rather, as asection of the longitudinal axis of the ultrasonic probe 15 ispositioned in proximity to the biological material, the biologicalmaterial is removed in all areas adjacent to the plurality of nodes 50,60 and the plurality of anti-nodes 52, 62 that are produced by thetorsional vibration and transverse vibration along the active area ofthe ultrasonic probe 15, typically in a region having a radius of up toabout 6 mm around the ultrasonic probe 15. The torsional mode ofvibration and transverse mode of vibration results in an ultrasonicenergy transfer to the biological material with minimal loss ofultrasonic energy that could limit the effectiveness of the ultrasonicmedical device 11. In addition to increasing the biological materialdestroying area of the ultrasonic probe 15, the probe tip 9 is able toablate the biological material when the probe tip 9 encounters thebiological material and the ultrasonic probe 15 is vibrated torsionallyand transversely.

In one embodiment of the present invention, the ultrasonic probe 15 isswept along the treatment site of the biological material. In anotherembodiment of the present invention, the ultrasonic probe 15 is movedback and forth along the treatment site of the biological material. Inanother embodiment of the present invention, the ultrasonic probe 15 istwisted along the treatment site of the biological material. In anotherembodiment of the present invention, the ultrasonic probe 15 is rotatedalong the treatment site of the biological material. Those skilled inthe art will recognize the ultrasonic probe can be place incommunication with the biological material in many ways known in the artand be within the spirit and scope of the present invention.

Unlike the prior art longitudinal mode of operation where the biologicalmaterial destroying effects are limited to the tip of the probe, anactive area of the ultrasonic probe 15 operating in the torsional modeand transverse mode extends from the probe tip 9 and along a portion ofa longitudinal axis of the ultrasonic probe 15. The section belowentitled “Theory of Operation” discusses some differences between thelongitudinal mode of operation used in the prior art and the torsionalmode and transverse mode of operation used in the present invention. Inthe torsional mode and transverse mode of vibration, the biologicalmaterial is removed in all areas adjacent to the plurality of nodes 50,60 and the plurality of anti-nodes 52, 62 that are produced by thetorsional vibration and transverse vibration along the active area ofthe ultrasonic probe 15. By treating a larger area of the treatment siteof the biological material, the ultrasonic medical device 11 of thepresent invention allows for shorter medical procedures. By reducing thetime of the medical procedure, a patient is not subjected to additionalhealth risks associated with longer medical procedures.

FIG. 10 shows the ultrasonic probe 15 of the present invention extendingfrom a distal end 34 of a sheath 36. As shown in FIG. 10, the ultrasonicprobe 15 is placed within the sheath 36, which can provide an at leastone irrigation channel 38 and an at least one aspiration channel 39. Inan embodiment of the present invention, irrigation is provided betweenthe ultrasonic probe 15 and the sheath 36. The ultrasonic probe 15 maybe moved in an axial direction within the sheath 36 to move the distalend 24 of the ultrasonic probe 15 axially inwardly and outwardlyrelative to the distal end 34 of the sheath 36. By extending orretracting the ultrasonic probe 15 relative to the sheath 36, the amountof the ultrasonic probe 15 exposed is modified, thereby modifying thebiological material destroying area of the ultrasonic probe 15.

In an embodiment of the present invention, the sheath 36 is comprised ofpolytetrafluoroethylene (PTFE). In another embodiment of the presentinvention, the sheath 36 is comprised of teflon tubing or similarfluoropolymer tubing. The sheath absorbs the ultrasonic energy emanatingfrom the portions of the ultrasonic probe 15 located within the sheath36, thereby allowing control over the amount of biological materialaffected by the ultrasonic probe 15. The sheath 36 is preferablycomprised of a material which is resistant to heat from the ultrasonicenergy, even though the irrigation fluid can act as a coolant for thesheath 36.

The present invention provides a method of treating a biologicalmaterial in the body with the ultrasonic medical device 11. Theultrasonic probe 15 of the ultrasonic medical device 11 is moved to thetreatment site of the biological material and placed in communicationwith the biological material. The ultrasonic energy source 99 of theultrasonic medical device 11 engaged to the ultrasonic probe 15 isactivated to produce the torsional vibration of the ultrasonic probe 15.The transducer engaging the ultrasonic energy source 99 at the proximalend of the transducer and the ultrasonic probe 15 at the distal end ofthe transducer creates the torsional vibration along the longitudinalaxis of the ultrasonic probe 15. The torsional vibration of theultrasonic probe 15 induces the transverse vibration in the active areaof the ultrasonic probe, wherein the active area of the ultrasonic probe15 supports the torsional vibration and the transverse vibration.

The present invention also provides a method of removing a biologicalmaterial in the body. The ultrasonic probe 15 of the ultrasonic medicaldevice 11 is moved in the body and placed in communication with thebiological material. The ultrasonic energy source 99 of the ultrasonicmedical device 11 produces an electric signal that drives the transducerof the ultrasonic medical device 11 to produce a torsional vibration ofthe ultrasonic probe 15. The torsional vibration of the ultrasonic probe15 induces the transverse vibration along the longitudinal axis of theultrasonic probe 15, creating a plurality of nodes 50, 60 and aplurality of anti-nodes 52, 62 along an active area of the ultrasonicprobe 15.

Theory of Operation

The torsional mode of vibration and transverse mode of vibration of thepresent invention differs from longitudinal mode of vibration of theprior art. In the longitudinal vibration of the prior art, thefrequencies of the individual modes depend on the modulus of elasticityE and the density ρ.

$c_{l} = \sqrt{\frac{E}{\rho}}$

For the torsional waves, the expression is the same except the shearmodulus, G, is used instead of the modulus of elasticity, E. The shearmodulus, G, and the modulus of elasticity, E, are linked throughPoisson's ratio υ:

$G = \frac{E}{2( {1 + \upsilon} )}$

and the corresponding torsional speed of propagation is:

$c_{t} = \sqrt{\frac{{GK}_{T}}{\rho \; I}}$

where K_(T) is the torsional stiffness factor of the cross section and Iis the moment of inertia of the cross section. For a circular crosssection the ratio K_(T)/I=1, while for radially asymmetric crosssections the ratio K_(T)/I<1. Therefore, the speed of propagation willbe slower for the torsional wave by a factor of:

$\frac{c_{t}}{c_{l}} = \sqrt{\frac{K_{T}}{2( {1 + \upsilon} )I}}$

For a symmetric cross section K_(T)/I=1, and for a radially asymmetriccross section K_(T)/I<1. For common metals, Poisson's ratio υ is on theorder of 0.3, therefore the speed of propagation for a torsional wavewill be approximately 62% or less of that for the longitudinal wave. Adecrease in the speed of propagation implies a proportional decrease inthe wavelength for a given frequency. Decreasing the wavelength greatlyimproves the devices ability to deliver energy through the tortuouspaths and the tight bends of the vasculature.

The operating frequencies of the longitudinal and torsional modes aredependent on the properties of the ultrasonic probe. Selection ofmaterial properties depends primarily on acoustic loss, the choice ofoperating frequency and the desired amplitude of vibration. As discussedpreviously, with the ultrasonic probe comprised of titanium andoperating at a frequency of about 20 kHz, the torsional wave speed for acircular cross section is as follows:

$c_{t} = {\sqrt{\frac{\frac{E}{2( {1 + v} )}}{\rho}} = \sqrt{\frac{\frac{1.1 \times 10^{11}\mspace{14mu} {Pa}}{2( {1 + 0.3} )}}{4600\mspace{14mu} {kg}\text{/}m^{3}} = {3032\mspace{14mu} m\text{/}s}}}$

Using the torsional wave speed to solve for a condition of the length ofthe ultrasonic probe to operate in a torsional mode and a transversemode gives:

$L = {\frac{\lambda}{2} = {\frac{c}{2\; f} = {\frac{3032\mspace{14mu} m\text{/}s}{2( {20,000\mspace{14mu} {Hz}} )} = {{0.0758\mspace{14mu} m} = {{7.58\mspace{14mu} {cm}} \approx {3\mspace{14mu} {{in}.}}}}}}}$

Thus, for the ultrasonic probe to operate in a torsional mode and atransverse mode, the length of the ultrasonic probe should not be aninteger multiple of 7.58 cm (about 3 inches) for this particular case.Those skilled in the art will recognize that changes to other materialproperties can influence the operation in the torsional mode and thesechanges are within the spirit and scope of the present invention.

The present invention provides an apparatus and a method for anultrasonic medical device operating in a torsional mode and a transversemode. The active area of the ultrasonic probe is vibrated in a directionnot parallel to the longitudinal axis of the ultrasonic probe whileequally spaced points along the active area are vibrated back and forthin a short arc along the active area of the ultrasonic probe. Thepresent invention provides an ultrasonic medical device that is simple,user-friendly, time efficient, reliable and cost effective.

All patents, patent applications, and published references cited hereinare hereby incorporated herein by reference in their entirety. Whilethis invention has been particularly shown and described with referencesto preferred embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the scope of the invention encompassed by theappended claims.

1. An ultrasonic medical device comprising: an ultrasonic probecomprising a proximal end, a distal end and a longitudinal axistherebetween; and a transducer coupled to the ultrasonic probe, thetransducer being configured to create a torsional vibration along theultrasonic probe, the ultrasonic probe and the transducer being adaptedso that the torsional vibration induces a transverse vibration along aportion of the ultrasonic probe.
 2. The ultrasonic medical device ofclaim 1 wherein the transverse vibration is tuned into coincidence withthe torsional vibration along the portion of the ultrasonic probe inwhich the transverse vibration is induced.
 3. The ultrasonic medicaldevice of claim 1 wherein tension to the ultrasonic probe tunes thetransverse vibration into coincidence with the torsional vibration. 4.The ultrasonic medical device of claim 1 wherein bending the ultrasonicprobe tunes the transverse vibration into coincidence with the torsionalvibration.
 5. The ultrasonic medical device of claim 1 wherein thetorsional vibration and the transverse vibration are segregated over theportion of the ultrasonic probe.
 6. The ultrasonic medical device ofclaim 1 wherein the torsional vibration of the ultrasonic probe producesa plurality of torsional nodes and a plurality of torsional anti-nodesalong the portion of the ultrasonic probe.
 7. The ultrasonic medicaldevice of claim 1 wherein the torsional vibration of the ultrasonicprobe causes a rotation and counterrotation along at least the portionof the ultrasonic probe.
 8. A medical device comprising: an elongated,flexible probe comprising a proximal end, a distal end and alongitudinal axis between the proximal end and the distal end; atransducer coupled to the elongated, flexible probe, the transducerbeing configured to create a torsional vibration along the longitudinalaxis of the elongated, flexible probe when electrical energy is appliedto the transducer, the elongate, flexible probe and the transducer beingadapted so that the torsional vibration induces a transverse vibrationalong the longitudinal axis of the elongated, flexible probe.
 9. Themedical device of claim 8 wherein the transverse vibration is tuned intocoincidence with the torsional vibration along at least a portion of thelongitudinal axis of the elongated, flexible probe in which thetransverse vibration is induced.
 10. The medical device of claim 8wherein tension to the elongated, flexible probe tunes the transversevibration into coincidence with the torsional vibration.
 11. The medicaldevice of claim 8 wherein bending the elongated, flexible probe tunesthe transverse vibration into coincidence with the torsional vibration.12. The medical device of claim 8 wherein bending the elongated,flexible probe shifts a frequency of the elongated, flexible probecausing the transverse vibration to coincide with the torsionalvibration.
 13. The medical device of claim 8 wherein the torsionalvibration and the transverse vibration are superimposed or segregatedalong the longitudinal axis of the elongated, flexible probe.
 14. Themedical device of claim 8 wherein the elongated, flexible probecomprises a varying diameter from the proximal end of the elongated,flexible probe to the distal end of the elongated, flexible probe. 15.An ultrasonic probe comprising: a proximal end; a distal end thatterminates in a probe tip; and a longitudinal axis between the proximalend and the distal end, wherein the ultrasonic probe supports atorsional vibration and a transverse vibration.
 16. The ultrasonic probeof claim 15 wherein the transverse vibration is tuned into coincidencewith the torsional vibration along at least a portion of thelongitudinal axis of the ultrasonic probe in which the transversevibration is induced.
 17. The ultrasonic probe of claim 15 whereintension to the ultrasonic probe tunes the transverse vibration intocoincidence with the torsional vibration.
 18. The ultrasonic probe ofclaim 15 wherein bending the ultrasonic probe tunes the transversevibration into coincidence with the torsional vibration.
 19. Theultrasonic probe of claim 15 wherein bending the ultrasonic probe shiftsa frequency of the ultrasonic probe causing the transverse vibration tocoincide with the torsional vibration.
 20. The ultrasonic probe of claim15 wherein the ultrasonic probe comprises a varying cross section fromthe proximal end of the ultrasonic probe to the distal end of theultrasonic probe.